324 BULLETIN 120, UNITED STATES NATIONAL, MUSEUM. 



stocky, the other slender, much as in P. caudata and P. nutt'i, both 

 placed' in group 3, and its unciliated, tail-like, posterior tip em- 

 phasizes this resemblance, but the condition of its macrochromatin, 

 especially in the metaphase stage of mitosis, is somewhat different 



from that in the caudata group. The life cycle and its relations 

 to the young and the adult of the host also are different, for P. 

 saturnalls reproduces sexually in the same individual adult hosts m 

 which the adult parasites are found, and apparently the sexual 



